Quality assessment of studies included in Cochrane oral health systematic reviews

Objectives: The Risk of Bias (RoB) and other characteristics of randomized clinical trials included in Cochrane oral health systematic reviews were assessed. Study Design and Settings: All the trials included in Cochrane oral health systematic reviews were examined. The RoB was evaluated for all the included clinical trials according to the Cochrane review standards. The Overall Risk of Bias (ORoB) was defined in this study based on the criteria for determining the overall bias in Cochrane9s RoB tool-v2. Descriptive analyses were carried out to determine the frequency of each intended variable. Results: A total of 2565 studies were included in our analysis. The majority of the studies (n=1600) had sample sizes of 50 or higher. As for blinding, 907 studies were labelled as double-blind. Performance bias showed the highest rate of high risk (31.4%). Almost half of the studies had a high ORoB compared to 11.1% with low ORoB. The studies that used placebos had higher low ORoB (14.8% vs. 10.7%). The double-blind studies had the highest low ORoB (23.6%). The studies with a cross-over design had the highest low ORoB (28.8%). Conclusion: Overall, the RoB for the studies on dentistry and oral health in Cochrane reviews was deemed high.